The expanding shell around V445 Puppis

Using the NACO adaptive optics instrument on ESO’s Very Large Telescope and its ability to obtain images as sharp as if taken from space, astronomers have made the first time-lapse movie of a bipolar shell ejected by a “vampire star”, which underwent an outburst after gulping down part of its companion’s matter. This enabled them to determine the distance and intrinsic brightness of the object. It appears that this system is a prime candidate to be one of the long-sought progenitors of the exploding stars known as Type Ia supernovae, critical for the study of dark energy. The images of V445 Puppis cover a time span of two years. The images unambiguously show a bipolar shell, initially with a very narrow waist, with lobes on each side. Two knots are also seen at either extreme end of the shell, which appear to move at about 30 million kilometres per hour. The shell — unlike any previously observed for a nova — is itself moving at about 24 million kilometres per hour. A thick disc of dust, which must have been produced during the last outburst, obscures the central couple of stars.